/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.tsfile.read.reader.series;

import org.apache.iotdb.tsfile.file.metadata.IChunkMetadata;
import org.apache.iotdb.tsfile.read.common.BatchData;
import org.apache.iotdb.tsfile.read.controller.IChunkLoader;
import org.apache.iotdb.tsfile.read.filter.basic.Filter;
import org.apache.iotdb.tsfile.read.reader.IBatchReader;
import org.apache.iotdb.tsfile.read.reader.IChunkReader;

import java.io.IOException;
import java.util.List;

/**
 * Series reader is used to query one series of one tsfile.
 */
public abstract class AbstractFileSeriesReader implements IBatchReader {

    protected IChunkLoader chunkLoader;
    protected List<IChunkMetadata> chunkMetadataList;
    protected IChunkReader chunkReader;
    private int chunkToRead;

    protected Filter filter;

    /**
     * constructor of FileSeriesReader.
     */
    public AbstractFileSeriesReader(
            IChunkLoader chunkLoader, List<IChunkMetadata> chunkMetadataList, Filter filter) {
        this.chunkLoader = chunkLoader;
        this.chunkMetadataList = chunkMetadataList;
        this.filter = filter;
        this.chunkToRead = 0;
    }

    @Override
    public boolean hasNextBatch() throws IOException {

        // current chunk has additional batch
        if (chunkReader != null && chunkReader.hasNextSatisfiedPage()) {
            return true;
        }

        // current chunk does not have additional batch, init new chunk reader
        while (chunkToRead < chunkMetadataList.size()) {

            IChunkMetadata chunkMetaData = nextChunkMeta();
            if (chunkSatisfied(chunkMetaData)) {
                // chunk metadata satisfy the condition
                initChunkReader(chunkMetaData);

                if (chunkReader.hasNextSatisfiedPage()) {
                    return true;
                }
            }
        }
        return false;
    }

    @Override
    public BatchData nextBatch() throws IOException {
        return chunkReader.nextPageData();
    }

    protected abstract void initChunkReader(IChunkMetadata chunkMetaData) throws IOException;

    protected abstract boolean chunkSatisfied(IChunkMetadata chunkMetaData);

    @Override
    public void close() throws IOException {
        chunkLoader.close();
    }

    private IChunkMetadata nextChunkMeta() {
        return chunkMetadataList.get(chunkToRead++);
    }
}
